I have 3 days left on a 4 day Hopper Pass bought in January (I was at a continuing ed conference and events happened such that I wasn't able to use all 3 days on the pass)---and want to trade those in toward purchase of an Annual Pass for WDW. Are places such as AAA able to do this or is this option only available through WDW (either on-site or through one of their "official" outlets/ticket sellers)?